Erdos’ Number

The Erdos number, honoring the late Hungarian mathematician Paul Erdos, is a way of describing the “collaborative distance” between a person and Erdos, as measured by authorship of mathematical papers.
In order to be assigned an Erdos number, an author must co-write a mathematical paper with an author with a finite Erdos number. Paul Erdos is the one person having an Erdos number of zero. If the lowest Erdos number of a coauthor is k, then the author’s Erdos number is k + 1.

Marco Cagnazzo has an Erdos number less or equal to five through the following connections: